Manchester United have no margin for error if they are to secure a top-four Premier League finish and qualify for the Champions League, manager Louis van Gaal said on Tuesday.

Fifth-place United trail Manchester City and Arsenal by four points ahead of their league game against potential FA Cup final opponents Crystal Palace at Old Trafford on Wednesday.

File picture of Louis Van Gaal. Reuters

City and Arsenal play each other before the end of the season, which gives United additional hope of making the top four and potentially keeping Van Gaal in a job for the final year of his contract.

But the Dutchman admits that that could be irrelevant if United slip up against Palace and do not take maximum points from their final five games.

"They have four points more than us," Van Gaal said. "We are dependent on them, we know that. We can only look at ourselves. You can only give pressure by winning so we have to look to ourselves.

"The most important thing is to win this game. I have already explained why we must win to close the gap, otherwise it is too big for the amount of matches we have to play.

"The experience in the Premier League is that our competitors also lose. A lot of teams are losing and we have to look for the finishing five matches to win this.

"(But) we have to look to ourselves, we have to win. We must win, otherwise we cannot close the gap."

United and Palace both play in the FA Cup semi-finals this weekend, with United facing Everton on Saturday and Palace taking on Watford on Sunday.

United have not won the tournament since 2004 and Van Gaal is determined to maintain his record of winning a trophy with every club that he has managed.

Shaw short

But he says that the focus has to be on trying to beat Palace first to stay in the hunt for Champions League football and has pledged not to rest players ahead of the trip to Wembley.

"I have always an eye on the schedule of my team because I have to look if the load is not an overload for the players," he told reporters at United's Carrington training base.

"I have done that all season, but I couldn't do that at all times because we have a lot of injuries so I didn't rotate so much.

"This game against Crystal Palace is very important. We have to win, we need to win, so it's much more important to win this game than, for example, for Arsenal or Manchester City.

"They have that gap of four points (on) us. It's too important to rotate for freshness for the semi-final. No, we have to win.

"For me, now, the most important thing is to beat Crystal Palace. To speak about the semi-final against Everton isn't appropriate."

United's England defender Luke Shaw has returned to training after recovering from a broken leg sustained last September, but Van Gaal believes the 20-year-old is still some way short of a return to first-team duty.

"He's very positive," Van Gaal said. "He's going great, I cannot deny that. He's training on the pitch. Now he's training with the physios and he has to train with the football coach and that's still not happening."

Shaw will therefore miss the visit of mid-table Palace, while Adnan Januzaj and Bastian Schweinsteiger are also still out, but Ander Herrera returns after missing last Saturday's 1-0 win over Aston Villa.